The present invention relates generally to fuel pumps and more particularly to fuel pump devices which reduce corrosion of the outlet terminals.
Fuel pumps are commonly used to transfer fuel from a remotely positioned fuel tank to an internal combustion engine. Many different types of fuel pumps are known for accomplishing this purpose. One of the more well known fuel pumps is an electric fuel pump. Current electric fuel pumps are typically positioned within the fuel tank and secured therein. These fuel pumps are typically connected to a power and control source which is located outside the fuel tank. The power and control source is typically connected to the fuel pump by a wire harness. The wire harness is attached to the electric fuel pump with electrical contacts.
The electrical contacts are typically exposed to fuel which can corrode the exposed area. Corrosion can cause durability issues for the electric fuel pump. Durability issues can result in increased costs and shortened life of the electric fuel pump.
As a result, durability is a primary concern of fuel pump design for use in automotive applications. Current designs, however, are frequently unable to provide the desired long life without the need for replacement parts or repair. Current design solutions include the use of press-fit plastic caps and rubber seals or O-rings. While these solutions have the effect of reducing contact with the fuel, they often allow some leakage when subjected to the vibrations and impacts of the automotive environment.
The introduction of flexible fuels makes achieving the desired durability even more difficult. Flexible fuels include corrosive fuels such as alcohol, methanol, and ethanol. Even minimal exposure to such fuels can lead to the rapid corrosion and failure of materials such as those used in the electrical connections that connect the electrical fuel pump to the wire harness. Even the small amount of leakage found in current designs can significantly reduce the life of a fuel pump in a corrosive environment. As the demand for flexible and alternative fuels continues to grow, the need for a fuel pump that can withstand the corrosive environment of these fuels is a necessity.
It is therefore the object of the present invention to provide an electrical outlet assembly for a fuel pump that significantly reduces exposure of the terminals to fuel. It is a further object of the present invention to provide an electrical outlet assembly for a fuel pump that prevents corrosion when used in the highly corrosive environment of flexible fuels.
In accordance with the objects of the present invention, an improved electrical fuel pump assembly is provided. The fuel pump includes a pump housing disposed in a fuel tank. The pump housing contains an inlet opening allowing fuel to enter the pump and an outlet opening allowing expulsion of fuel therefrom. A pumping apparatus, located within the pump housing and powered by an electric motor, forces the fuel into the inlet opening and out of the outlet opening. The electric motor, positioned within the pump housing, contains electrical terminals that mate outside the pump housing with a power source to supply power to the electric motor. The mating takes the form of a wire harness connecting the electrical terminals to the power source. A protective coating of thermoplastic covers the terminals and their connections to the wire harness to prevent contact with the fuel in the fuel tank.
The protective coating covering the terminals and their connection to the wire harness is applied through the use of an overmold process. The process consists of connecting the wire harness with the outlet assembly and inserting the combination into a mold cavity. The edges of the mold cavity are sealed and a thermoplastic resin is injected between the mold and the outlet assembly. The result is a thermoplastic coating that seals the entire electrical outlet assembly and its connection to the wire harness.
Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.